1. Field of the Invention
The present invention relates to a game apparatus for causing a player object and a field object that are present in a virtual game space to be displayed in a display device and to a computer-readable storage medium having stored therein a game program, and particularly relates to a game apparatus for controlling the orientation of a player object in a virtual game space, based on the motion applied to an input device itself, and to a computer-readable storage medium having stored therein a game program.
2. Description of the Background Art
Conventionally, a game apparatus using the angular velocity detected by a gyro sensor is known (Japanese Laid-Open Patent Publication No. 2006-68027, for example). This game apparatus includes a housing capable of being held by a player, a display screen provided in the housing, and a gyro sensor for detecting the angular velocity around the axis vertical to the display screen. When the player rotates the game apparatus itself around the axis vertical to the display screen, the rotation angle of the housing is calculated based on the detected angular velocity, whereby a game image is rotated in accordance with the calculated rotation angle.
In the game apparatus described above, the gyro sensor constantly outputs some values even when not rotating, and therefore, to calculate the actual angular velocity value when rotating, an angular velocity value outputted from the gyro sensor when not rotating is set as an initial value of a neutral position value and stored. Since the neutral position value thus set may deviate due to the characteristics of the gyro sensor, a correction process of the value is also performed. For example, when it is determined that a plurality of angular velocity values acquired in a predetermined time are constant, it is determined whether or not there is a difference between this constant value and the neutral position value. When it is determined that there is a difference, the neutral position value is corrected so as to perform a process of providing the player with a comfortable sense of playing.
However, the game apparatus described above has the following problems. Generally, a game using a gyro sensor is likely to be affected by the accumulation of errors of the angular velocity detected by the gyro sensor. In response, the game apparatus described above requires adjustments such as the neutral position and the correction process, but these adjustments are complicated for game processing. Further, in the game apparatus described above, since the correction process is performed, for example, using the plurality of angular velocity values acquired in the predetermined time, the error caused by a drastic change in angular velocity cannot be absorbed.